Association Forum - Troubleshooting an Evinrude 10 hp two stroke

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Troubleshooting an Evinrude 10 hp two stroke

New Topic

Topic Locked

Printer Friendly

Author

Topic

keithsinger
1st Mate

Member Avatar

USA
29 Posts

Initially Posted - 05/13/2013 : 21:31:14

I wrote in an earlier topic about cruising with my wife and toddler at Lake Powell this past Mother's Day weekend. It was a great trip. I updated the original posting this morning while on our way back to the marina and pull-out ramp with a trip report that said the outboard worked like a top. Truth is, about an hour after I wrote that, I experienced the beginnings of engine failure due to fouled plugs. It started as a missed beat on the engine, and increased over time to rough running. I pretty much know it was fouled plugs because the same thing happened to me the last time I went cruising, also after around 80-100 miles on the engine. That time I was still about 10 miles offshore and the engine gradually stopped running and I had to open the engine cover, take the plugs out and clean them several times in the heat and humidity before I got the engine running to take me the last miles across the Sea of Cortez. For this past weekend's trip to Powell, I installed brand new plugs. I just can't accept that one has to change or clean the spark plugs on an '86 Evinrude 10 hp two stroke engine every 15 hours or so of engine time. I've got a two stroke scooter that never fouls plugs. I'm thinking either I've got the rich/lean dial to rich, or I'm putting too much oil in my gas. Frankly, I'm not sure how the lean rich dial works. Is it lean when it is pointing to the narrow part of the dial or is it lean when pointing to the wider part of the indicator? I can't seem to observe a difference in how the engine runs either way. As to oil in the gas, I use roughly 4 oz per gallon. I think that's 1 part oil to 50 parts gas? I read somewhere that it is also possible to use 1/100, but I don't want to burn the engine up. My wife thinks I'm using too much two stroke oil. I really want to keep this engine. When the plugs are not fouling, it actually does run like a top and seems very reliable. It is a long shaft and has electric start and a built in charger and it just took us well over 100 miles of non-stop engine cruising. We made it all the way back and to the dock this time, but if I had to go another 5 or 10 miles, I'm sure the plugs would have fouled to the point where the engine wouldn't run and I'd have been out there in the hot sun with wife and baby pulling plugs and cleaning them. I think this was a popular engine on Catalina 25 of 1980's vintage, so I would appreciate any ideas or personal experience with this engine or two stroke engines like mine.

Boker Tov 1987 Catalina 25 Wing Standard Rig http://www.sailblogs.com/member/lemmonsway/

Edited by - keithsinger on 05/13/2013 21:35:51

hubbardbilly
1st Mate

Members Avatar

USA
44 Posts

Response Posted - 05/14/2013 : 00:48:00

I have a 96 Evinrude 2 stroke 10HP on my 78 C25. I have owned multiple 2-stroke engines (mostly motorcycles) and what I can offer is this:
- My evinrude asks for 50:1 ratio, which is pretty much standard from my experience. If you're not sure what ratio you're mixing, buy one of those "mix calculator" bottles that tell you how much oil to put in a set amount of fuel. Takes the guessing out of it.
- The rich/lean adjustment is typically set by a number of turns "out" from the carb. The shop manual for the outboard will tell you where to initially set it. Fine adjustments to this screw can significantly impact how fast the plugs foul.
- Running at low engine rpm over time can also increase plug fouling.
- Make sure the plugs are gapped properly per the owners manual. This ensures the right amount of spark/heat in the cylinder which also minimizes fouling.
- Bring spare plugs. Gap them ahead of time.

Edited by - on

CarbonSink62
Navigator

Members Avatar

USA
208 Posts

Response Posted - 05/14/2013 : 07:32:29

4oz per gallon is too much; 2.6 (or less) is recommended.

I had a 'senior moment' last season and added about 3.5oz/g; it ran fine for 3/4 of that tank then the plugs fouled. Ran fine the rest of the season w/ 2.6/g.

I never got my rich/lean correct (or maybe I did) the book says to back it out x turns; start the engine; back it out more until the engine 'runs rough'; then go in until it runs smooth again.

Even backed out several turns, my engine never ran rough. Since the engine did run smooth, I put it on the back of the boat.

Edited by - on

KenDavis
1st Mate

Members Avatar

USA
69 Posts

Response Posted - 05/14/2013 : 08:42:43

I have a mid 90's version of that engine.
I was having similar issues recently usually losing one cylinder at first and soon after the next. plugs would be fouled etc.

I swapped the coil unit and two plug wires from some spares that I have and the problem went away.

as for fuel oil mix ratio I use the ratio rite type mix cups and split the difference between 1:50 and 1:100 (1:75ish?)however I use synthetic 2 stroke oil.

Edited by - on

Sloop Smitten
Master Marine Consultant

Members Avatar

USA
1181 Posts

Response Posted - 05/14/2013 : 09:23:13

Correct mixture is 50:1 or 2.56 oz. per gallon. Your running 32:1. Regarding the lean/rich dial, (ccw) left is rich and (cw) right is lean. Get the oil mix right and center the carburetor dial. Check the plugs after an hours use and adjust the knob as necessary. Plugs are cheap. Get a new pair and you can swap them out quickly if they foul and then clean the fouled plugs as time permits. Make sure you have the proper plugs (Champion QL82C) and gap (.030") for the engine and that someone did not install incorrect ones at some time. For clarity's sake the engine is a 9.9HP. Engine manufacturers make 9.9 HP engines to help owners avoid registering the outboard in those states that require registration on outboard engines 10HP and above.

Edited by - on

vipermagic
1st Mate

Members Avatar

USA
69 Posts

Response Posted - 05/16/2013 : 14:03:49

This site is full of great, if a little hidden and rambley, information about those specific outboards:

http://www.leeroysramblings.com/Outboard%20Motor%20Related/OMC%20outboard%20related%20articles.html

Edited by - on

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.